Cable sheathing press



Sept. 30', 1969 R. DEINA 3,469,431

CABLE SHBATHING PRESS Filed Aug. 22, 1966 /NVNTOR RuDoL F DE I N A ATTOKAMY;

United States Patent US. Cl. 72-268 4 Claims ABSTRACT OF THE DISCLOSURE A mandrel, through which a cable to be sheathed is passed, comprises a hollow mandrel body which has a sheathing die entry end with an outer tip portion which is adapted to be located directly adjacent the sheathing die for the delivery of the cable therethrough to the die. The mandrel includes a guide for the cable formed on the interior of the mandrel which include means for cooling the cable on the mandrel side before the cable is delivered to the location at which the sheathing material is added to the exterior of the cable. The cooling is such that the mandrel tip which is directly adjacent the sheathing die, will remain hot so that the metal flowing to the sheathing point will be unaffected. The cooling is necessary in order that the guide for the cable functions to permit feeding of the cable uniformly and without burning the insulation covering over the cable.

This invention relates in general to sheathing presses for cables and in particular to a new and useful device for applying, for example, an aluminum sheath over a cable which device includes a mandrel which is arranged adjacent a sheathing die the mandrel having an interior projection which is adapted to bear against the advancing cable for centering the movement thereof and which includes internal means for cooling this element in order to insure that the temperatures do not become sufficiently high to causing burning of the so-called insulation material around the cable.

In the manufacture of cables with an aluminum sheath, it is always cause for concern that it might be possible that the temperatures become sufficiently high at the heating point between the mandrel and the die to cause the outer covering of the cable, the so-called insulation to burn. For the formation of a satisfactory sheath the front end of the mandrel must be kept relatively hot. On the other hand, the cable must be guided into the vicinity of the sheathing point to prevent a unilateral formation of the sheath. In order to protect the cable insulation the diameter of the guide formed by the front end of the hollow mandrel has been made larger than the cable diameter. It has been observed, however, that in the case of more sensitive insulation, the phenomenon of combustion will occur nevertheless and this must be positvely avoided.

A known solution of the problem consists in placing the guide for the cable away from the mandrel rod so that the front end of the hollow mandrel no longer comes in contact with the cable. The guide is then a separate cooled pipe which is centered in relation to the mandrel. With this solution it is inevitable that the guide is relatively far removed from the cable sheathing point so that there is a danger of unilateral formation of the sheath by displacement of the cable core. In addition, there will be difliculties in obtaining alignment between the long heat-protected pipe carrying the guide with the mandrel.

In accordance with the invention, the guiding and centering of the cable is achieved by the mandrel itself which, however, is provided with a cylindrical extension which provides means for guiding and centering the cable in respect to the sheath which is to be fed through the die. The extension is arranged in contact with and embraced by a protective and cooling pipe extending from the inlet side. The mandrel and the mandrel tip are protected with this construction from notable cooling which would make the sheathing process impossible. It has been found that by placing the cable guide in the mandrel extension and by cooling the extension, the temperatures can be maintained and controlled so that a great drop of temperature from the front end of the mandrel to the guide extension can be effected. In this way it is possible for the cable sheathing process to be carried out in a continuous operation, that is, presses without stopping. It is also possible to maintain the exit temperature of the cable sheathing material which is of aluminum sufficiently high between the mandrel rod and the die and to obtain the guiding of the cable through the mandrel rod into the die. Thus the cable is guided directly by the mandrel rod and the guide is situated as close to the sheathing point as possible.

The mandrel extension is formed as a guide which should guide the cable with the least possible tolerance. This depends, among other things, on the construction of the cable core, on the desired insulation, and on the nature of the outer surface of the cable or respectively of the insulation. If the press is to sheath cables of different types, it is advisable to make the extension of the mandrel rod insertable and exchangeable. It can then be adapted to the various types of cables. The insertability of the extension may be desirable also for maching reasons. It also offers an advantage that the extension can be made of a different material for example one of better heat conduction than the remaining mandrel rod body. In this case a heat insulation material of a known kind may be provided between the mandrel rod and the cable guide designed as a sleeve.

Accordingly, it is an object of the invention to provide a cable sheathing press which includes a mandrel having an extension with a projection which bears in a direction opposite to the die against the advancing cable in order to provide a centering and alignment thereof and which includes means for cooling the bearing point so that the temperature at the die will not become excessive.

A further object of the invention is to provide a sheathing press which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

The only sheet of the drawings is a partial sectional view of a cable sheathing press constructed in accordance with the invention.

Referring to the drawing in particular, the invention embodied therein comprises a sheathing press which includes a hollow mandrel 1 arranged adjacent the die 2 for feeding sheathing material at the location U around the mandrel tip 4 and into the die. The cable 3 with the insulation material wrapped therearound is threaded into the mandrel 1 in the direction of the arrow indicated.

A feature of the construction is that the mandrel 1 on its outlet side 5 is provided with an inside diameter which is considerably greater than the diameter of the threaded cable 3. The mandrel is also provided with an inwardly and rearwardly extending extensions 7 which extend counter to the direction of movement of the cable 3 and bears against the cable at a location 6 which is removed from the front end 4 of the mandrel. The inside diameter of the extension 7 depends on the cable diameter and is so dimensioned that it provides a sole guide means and centering for the threaded cable 3 in the vicinity of the sheathing point.

A cooling pipe 8 extends into the hollow mandrel 1 and is provided with an opening 8 adjacent the extension for cooling the extension 7 and the area 6 immediately surrounding this extension. In this manner the guiding of the cable is carried out by the hollow mandrel itself at a point which is far removed from the cable sheathing point U. In addition the cable is guided at a point which is removed from the hot end 4 of the mandrel.

As a variation of the described embodiment, the extension 7 may be designed as a sleeve which is firmly inserted in a front portion 4 of the mandrel and a known heat insulation material may be provided between the mandrel tip and the guide extension 7 in order to increase the temperature drop from the tip 4 to the guide 7 if necessary. The cooling is provided in any event.

In some instances an additional guiding pipe 9 is provided at a location inwardly remote from the location of the inward extension 7.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A mandrel construction for cooperation with a sheathing die in a cable sheathing press comprising a hollow mandrel body having a sheathing die entry end with an outer tip portion adapted to be located adjacent the sheathing die and having an internal diameter greater than the size of the cable to be sheathed, said mandrel including an inwardly extending portion at a location spaced from the outer tip of said mandrel which is of a diameter substantially the same as the diameter of the cable to be sheathed and provides a centering means and guide for the cable, and means for directing a cooling fluid in the vicinity of the inward extension in order to maintain the extension at a temperature considerably below the temperature of the mandrel tip adjacent the die.

2. A mandrel construction according to claim 1 wherein said means for cooling said extension includes a cooling pipe extending into the interior of said mandrel and having an opening adjacent the extension for directing cooling fluid Within the interior of the mandrel at such location.

3. A mandrel construction according to claim 1 including a second centering member located within said mandrel for centering and guiding a cable therethrough.

4. A mandrel construction according to claim 1 wherein said extension is an inwardly extending wall portion of said mandrel.

References Cited UNITED STATES PATENTS 1,741,815 12/1929 Boynton 72-268 2,002,690 5/1935 Carter 72-271 2,161,570 6/1939 Harris 72-253 2,207,405 7/1940 Jacobson 72-271 2,214,016 9/1940 Duclos 72-271 2,385,574 9/1945 Hyprath 72-268 3,040,884 6/1962 Haendler 72-268 3,073,441 l/1963 Priaroggia 72-268 3,120,305 2/1964 Linnerz 72r-268 CHARLES W. LANHAM, Primary Examiner L. A. LARSON, Assistant Examiner 

